赣南茅坪钨矿流体包裹体研究

Study on the Fluid Inclusions of Maoping Tungsten Deposit,Southern Jiangxi Province

赣南茅坪钨矿是近年来探明的一个大型钨锡多金属矿床,矿床由石英脉型矿体和云英岩化花岗岩型矿体组成。本文在详细的岩相学观察基础上,对该矿床含矿石英脉石英和黄玉中的流体包裹体进行了显微测温和拉曼探针分析,并尝试用红外显微镜对黑钨矿中的流体包裹体进行了显微测温。结果表明,石英和黄玉中的流体包裹体主要为富液相的两相(H2O-NaCl)型水溶液包裹体,其中石英中尚有极少量的含CO2三相水溶液包裹体。石英中流体包裹体的均一温度、盐度范围较宽且均一温度分为较为明显的两个区间,石英中含CO2三相水溶液包裹体的均一温度与富液相两相水溶液包裹体的高温区间较为一致,盐度则明显低于后者,但均一方式不同。黑钨矿中流体包裹体的均一温度及盐度最高,黄玉中流体包裹体的均一温度及盐度较高且分布范围较窄。石英中流体包裹体的均一温度、盐度特征表明了成矿作用的多阶段性和流体演化的复杂性。流体包裹体特征表明,流体的早期沸腾作用和晚期混合作用可能是茅坪钨矿床石英脉型黑钨矿形成的主要机制。

Maoping tungsten deposit is a large W-Sn-polymetallic deposit discovered recently in southern Jiangxi Province.It comprises two types of ore-bodies,i.e.quartz-vein type and greisenized-granite type.This paper studies the fluid inclusions in quartz and topaz occurring in wolframite-quartz-veins,which mainly includes microthermometry and Laser Raman analysis.Besides,the homogenization temperatures of fluid inclusions in wolframite were determined under an infra-red microscope.Results show that fluid inclusions in both quartz and topaz are mainly liquid-rich two-phase aqueous solution （H 2 O-NaCl）,in addition to small amount of CO 2 -bearing three-phase aqueous solution in quartz.The homogenization temperatures from quartz show a wider range variations and can be divided into two main periods,indicating two stages of ore precipitation.The CO 2 -bearing three-phase inclusions have homogenization temperatures similar to those of the higher temperature period of the above inclusions,but lower salinities and different homogenizing ways.Fluid inclusions in wolframite have highest homogenization temperatures and salinities,whereas those in topaz also show high homogenization temperatures and salinities,and narrow variation range.The characteristics of homogenization temperatures and salinities from fluid inclusions in quartz reveal multiple-stages of ore-forming process and the complexity of fluid evolution.It is concluded from fluid inclusions that the early-stage boiling and late-stage mixing are probably the major mechanism of formation of wolframite-quartz-vein type ore in the Maoping deposit.